CV
Education
- Cornell University, Ithaca, NY
- Ph.D. in Operations Research: May 1995
- Major: Optimization
- Minors: Computer Science; Statistics
- Thesis: Parallel Branch and Cut for Vehicle Routing
- Thesis advisor: Dr. Leslie E. Trotter, Jr.
- Carnegie Mellon University, Pittsburgh, PA
- M.S. in Mathematics and B.S. in Applied Mathematics (with University Honors): May 1991
- Concentration: Operations Research
Current Positions
- Professor, Industrial and Systems Engineering, Lehigh University, Bethlehem, PA, October 2014 – July 2017
- Co-founder and Director, The Laboratory for Computational Optimization Research at Lehigh (COR@L), September 2004 – present
- Co-founder, Board Member, and Chair of the Technical Leadership Council, COIN-OR Foundation , March 2004 – present
- Founding Chair and Member, Lehigh Research Computing Steering Committee, January 2002 – present
- Member, MIPLIB 2017 Steering Committee, July 2016 – present
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August 2019
- Area Editor, Software Tools, INFORMS Journal on Computing, , January 2020 – present
- Technical Editor, Mathematical Programming Computation, August 2008 – present
- Associate Editor, IIE Transactions, January 2014 – present
Previous Positions
- Associate Editor, INFORMS Journal on Computing, September 2018 – December 2019
- Program Chair and Organizer, Industrial and Systems Engineering, Lehigh University, Bethlehem, PA, August 2017 – August 2018
- Visiting Researcher, Zuse Institute Berlin, July 2016 – July 2017
- Chair, INFORMS Computing Society, January 2014 – December 2015
- Sponsored Programs Chair, INFORMS Annual Meeting, Philadelphia, PA, November 2015
- Associate Professor, Industrial and Systems Engineering, Lehigh University, Bethlehem, PA, June 2006 – October 2014
- Associate Editor, Operations Research Letters, January 2004 – June 2014
- Vice Chair, INFORMS Computing Society, January 2012 – December 2013
- Board Member, INFORMS Computing Society, January 2010 – January 2012
- Editorial Board Member, Algorithmic Operations Research, August 2004 – December 2012
- Associate Editor, Operations Research, January 2005 – January 2011
- Editorial Board Member, The Open Operational Research Journal, January 2007 – January 2011
- Program Chair, MIP 2011, University of Waterloo, June 2011
- Co-director of Graduate Programs, Industrial and Systems Engineering, Lehigh University, September 2006 – December 2010
- Vice Chair for Computational Optimization and Software, INFORMS Optimization Society, 2007-2009.
- Visiting Professor, University of Newcastle, Spring 2009.
- Visiting Professor, Monash University, Spring 2009.
- Visiting Lecturer, Operations Research Society of New Zealand, Spring 2009.
- Senior Fellow, Institute for Advanced Studies, Università di Bologna, Bologna, Italy, Fall 2008.
- Vice President, Research and Development, Scalable OR Solutions, June 2004 – June 2007
- Assistant Professor, Industrial and Systems Engineering, Lehigh University, Bethlehem, PA, June 2000 – May 2006
- Postdoctoral Research Associate, Rice University, Houston, TX, September 1999 – August 2000
- United States Air Force, Nellis AFB, NV
- Chief, Tactics and Test Analysis, June 1997 – May 1999
- F-16 Lead Operations Analyst, June 1996 – May 1997
- Manpower Management Officer, June 1995 – May 1996
- Cornell University, Ithaca, NY
- Research Assistant, Summer 1991-3, January 1994 – May 1995
- Teaching Assistant, January 1992 – December 1993
Research Funding
- Efficient, Explainable and Robust Data Scientific Methods for Smart Engineering Systems, Lehigh Accelerator Grant.
- Multilevel Optimization with Bounded Rationality, Office of Naval Research Grant N00014-19-2330.
- COIN fORgery: Developing Open Source Tools for Operations Research, Institute for Mathematics and Its Applications, Grant to develop workshop and series of coding sprints.
- Optimization in an Uncertain World: A Unified Framework for Optimization Models Involving Adversaries, NSF Grant CMMI-1435453
- Computational Methods for Discrete Conic Optimization, NSF Grant DMS-1319893.
- Decomposition-Based Optimization: A New Solver Paradigm, NSF Grant CMMI-1130914
- Robust Planning of the Production of Liquid Gases Under Energy Uncertainty, Pennsylvania Infrastructure Technology Alliance (PITA) Grant
- Bilevel Integer Programming: Theory and Algorithms, NSF Grant CMMI-0728011
- Interdiction Problems: Detecting and Defending System Vulnerabilities, US Army, Communication Electronics Research Development and Engineering Center, Fort Monmouth.
- Advanced Computational Techniques for Optimization, SAS Institute
- Exploiting Cyberinfrastructure to Solve Real-time Integer Programs, NSF Grant DMI-0522796 (joint with Georgia Institute of Technology and University of Wisconsin)
- Duality and Warm Starting in Integer Programming, NSF Grant DMI-0534862
- Large Scale Optimization for Routing and Scheduling, Pennsylvania Infrastructure Technology Alliance (PITA) Grant
- Parallel Algorithms for Route Optimization, NSF Grant DMI-0441509
- Enterprise-wide Optimization, Pennsylvania Infrastructure Technology Alliance (PITA) Grant (joint with Carnegie-Mellon University and Air Products and Chemicals, Inc.)
- Open-source Software for Optimization, IBM Faculty Patnership Grant
- Scalable Parallel Algorithms for Discrete Optimization, NSF Grant ACI-0102687
Honors and Awards
- INFORMS Impact Prize, November 2014.
- Meritorious Service Award for Exception Contribution to the Journal Operations Research, August 2013.
- Visiting Lecturer, Operations Research Society of New Zealand, Spring 2009
- Senior Fellow, The Institute of Advanced Studies, Università di Bologna, Fall 2008
- Hillman Award for Excellence in Graduate Advising, May 2008
- First Open Contest of Parallel Programming, First Place, October 2007
- Sigma Xi Scientific Research Society, member, May 2003 – present
- Lehigh Engineering Ingenuity Award for Exceptional Accomplishment in Teaching and/or Research by Junior Faculty, April 2003
- IBM Faculty Partnership Award (three times), August 2001 – August 2004
- Rossin Assistant Professorship, June 2001 – June 2003
Refereed Publications
- S. Tahernejad, T. K. Ralphs, and S. T. DeNegre, “A Branch-and-Cut Algorithm for Mixed Integer Bilevel Linear Optimization Problems and Its Implementation,” Mathematical Programming Computation (to appear), 2019. [Software] [PDF] [Bibtex]
@Article{ TahRalDeN19, software = {https://github.com/tkralphs/MibS}, author = {Tahernejad, S. and Ralphs, T.K. and DeNegre, S.T.}, institution = {COR@L Technical Report 16T-015-R5}, journal = {Mathematical Programming Computation (to appear)}, title = {{A Branch-and-Cut Algorithm for Mixed Integer Bilevel Linear Optimization Problems and Its Implementation}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MIBLP16.pdf}, year = {2019} }
- T. K. Ralphs, Y. Shinano, T. Berthold, and T. Koch, “Parallel Solvers for Mixed Integer Linear Programing,” in Handbook of Parallel Constraint Reasoning, Y. Hamadi and L. Sais, Eds., Springer Berlin / Heidelberg, 2018, pp. 283-336. [PDF] [DOI] [Bibtex]
@InCollection{ RalShiBerKoc18, author = {Ralphs, T.K. and Shinano, Y. and Berthold, T. and Koch, T.}, booktitle = {Handbook of Parallel Constraint Reasoning}, chapter = {8}, doi = {https://doi.org/10.1007/978-3-319-63516-3_8}, editor = {Hamadi, Y and Sais, L}, organization = {COR@L Laboratory Report 16T-014-R3, Lehigh University}, pages = {283--336}, publisher = {Springer Berlin / Heidelberg}, title = {{Parallel Solvers for Mixed Integer Linear Programing}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ParallelMILPSurvey16.pdf} , year = {2018} }
- M. Miltenberger, T. K. Ralphs, and D. Steffy, “Exploring the Numerics of Branch-and-Cut for Mixed Integer Linear Optimization,” in Operations Research Proceedings: 2017, 2017. [PDF] [Bibtex]
@InProceedings{ MilRalSte17, author = {Miltenberger, M. and Ralphs, T.K. and Steffy, D.}, booktitle = {Operations Research Proceedings: 2017}, publisher = {Springer Berlin / Heidelberg}, title = {{Exploring the Numerics of Branch-and-Cut for Mixed Integer Linear Optimization}}, url = {https://opus4.kobv.de/opus4-zib/files/6464/numerics{\_}in{\_}mip.pdf} , year = {2017} }
- P. Belotti, J. C. Góez, I. Pólik, T. K. Ralphs, and T. Terlaky, “A Complete Characterization of Disjunctive Conic Cuts for Mixed Integer Second Order Cone Optimization,” Discrete Optimization, vol. 24, 2016. [Software] [PDF] [DOI] [Bibtex]
@Article{ BelGoePolRalTer16, abstract = {{\textcopyright} 2016 Elsevier B.V. We study the convex hull of the intersection of a disjunctive set defined by parallel hyperplanes and the feasible set of a mixed integer second order cone optimization (MISOCO) problem. We extend our prior work on disjunctive conic cuts (DCCs), which has thus far been restricted to the case in which the intersection of the hyperplanes and the feasible set is bounded. Using a similar technique, we show that one can extend our previous results to the case in which that intersection is unbounded. We provide a complete characterization in closed form of the conic inequalities required to describe the convex hull when the hyperplanes defining the disjunction are parallel.}, software = {https://github.com/aykutbulut/CGL-CONIC}, author = {Belotti, P. and G{\'o}ez, J.C. and P{\'{o}}lik, I. and Ralphs, T.K. and Terlaky, T.}, doi = {10.1016/j.disopt.2016.10.001}, issn = {15725286}, journal = {Discrete Optimization}, keywords = {Disjunctive conic cuts,Disjunctive programming,Mixed integer optimization,Second order cone optimization}, title = {{A Complete Characterization of Disjunctive Conic Cuts for Mixed Integer Second Order Cone Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ConicCuts14.pdf} , volume = {24}, year = {2016} }
- Y. Zhang, L. V. Snyder, T. K. Ralphs, and Z. Xue, “The Competitive Facility Location Problem Under Disruption Risks,” Transportation Research Part E: Logistics and Transportation Review, vol. 93, 2016. [PDF] [DOI] [Bibtex]
@Article{ ZhaSnyRalXue16, abstract = {{\textcopyright} 2016 Elsevier Ltd Two players sequentially locate a fixed number of facilities, competing to capture market share. Facilities face disruption risks, and each customer patronizes the nearest operational facility, regardless of who operates it. The problem therefore combines competitive location and location with disruptions. This combination has been absent from the literature. We model the problem as a Stackelberg game in which the leader locates facilities first, followed by the follower, and formulate the leader's decision problem as a bilevel optimization problem. A variable neighborhood decomposition search heuristic which includes variable fixing and cut generation is developed. Computational results suggest that high quality solutions can be found quickly. Interesting managerial insights are drawn.}, author = {Zhang, Y. and Snyder, L.V. and Ralphs, T.K. and Xue, Z.}, doi = {10.1016/j.tre.2016.07.002}, issn = {13665545}, journal = {Transportation Research Part E: Logistics and Transportation Review}, keywords = {Bilevel optimization,Competitive location,Facility disruptions,Local search,Variable neighborhood search}, title = {{The Competitive Facility Location Problem Under Disruption Risks}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CFLPD16.pdf}, volume = {93}, year = {2016} }
- P. Belotti, J. C. Góez, I. Pólik, T. K. Ralphs, and T. Terlaky, “A Conic Representation of the Convex Hull of Disjunctive Sets and Conic Cuts for Integer Second Order Cone Optimization,” in Numerical Analysis and Optimization, 2015. [PDF] [DOI] [Bibtex]
@InProceedings{ BelGoePolRalTer15, abstract = {{\textcopyright} Springer International Publishing Switzerland 2015. We study the convex hull of the intersection of a convex set E and a disjunctive set. This intersection is at the core of solution techniques for Mixed Integer Convex Optimization.We prove that if there exists a cone K (resp., a cylinder C) that has the same intersection with the boundary of the disjunction as E, then the convex hull is the intersection of E with K (resp., C). The existence of such a cone (resp., a cylinder) is difficult to prove for general conic optimization. We prove existence and unicity of a second order cone (resp., a cylinder), when E is the intersection of an affine space and a second order cone (resp., a cylinder). We also provide a method for finding that cone, and hence the convex hull, for the continuous relaxation of the feasible set of a Mixed Integer Second Order Cone Optimization (MISOCO) problem, assumed to be the intersection of an ellipsoid with a general linear disjunction. This cone provides a new conic cut for MISOCO that can be used in branch-and-cut algorithms for MISOCO problems.}, author = {Belotti, P. and G{\'o}ez, J.C. and P{\'{o}}lik, I. and Ralphs, T.K. and Terlaky, T.}, booktitle = {Numerical Analysis and Optimization}, doi = {10.1007/978-3-319-17689-5_1}, isbn = {9783319176888}, issn = {21941017}, keywords = {Conic cuts,Mixed integer optimization,Second order cone Optimization}, title = {{A Conic Representation of the Convex Hull of Disjunctive Sets and Conic Cuts for Integer Second Order Cone Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ConicCuts12.pdf} , volume = {134}, year = {2015} }
- A. Lodi, T. K. Ralphs, and G. Woeginger, “Bilevel Programming and the Separation Problem,” Mathematical Programming, vol. 148, pp. 437-458, 2014. [PDF] [DOI] [Bibtex]
@Article{ LodRalWoe14, author = {Lodi, A. and Ralphs, T.K. and Woeginger, G.}, doi = {10.1007/s10107-013-0700-x}, journal = {Mathematical Programming}, pages = {437--458}, title = {{Bilevel Programming and the Separation Problem}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BilevelSeparation12.pdf} , volume = {148}, year = {2014} }
- J. Wang and T. Ralphs, “Computational Experience with Hypergraph-based Methods for Automatic Decomposition in Discrete Optimization,” in Proceedings of the Conference on Constraint Programming, Artificial Intelligence, and Operations Research, 2013, pp. 394-402. [Software] [PDF] [DOI] [Bibtex]
@InProceedings{ WanRal13, abstract = {Branch-and-price (BAP) algorithms based on Dantzig-Wolfe decomposition have shown great success in solving mixed integer linear optimization problems (MILPs) with specific identifiable structure. Only recently has there been investigation into the development of a "generic" version of BAP for unstructured MILPs. One of the most important elements required for such a generic BAP algorithm is an automatic method of decomposition. In this paper, we report on preliminary experiments using hypergraph partitioning as a means of performing such automatic decomposition. {\textcopyright} Springer-Verlag 2013.}, software = {https://projects.coin-or.org/Dip}, author = {Wang, J. and Ralphs, T.}, booktitle = {Proceedings of the Conference on Constraint Programming, Artificial Intelligence, and Operations Research}, doi = {10.1007/978-3-642-38171-3_31}, isbn = {9783642381706}, issn = {03029743}, pages = {394--402}, title = {{Computational Experience with Hypergraph-based Methods for Automatic Decomposition in Discrete Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CPAIOR12.pdf} , year = {2013} }
- P. Belotti, J. C. Goez, I. Polik, T. K. Ralphs, and T. Terlaky, “On Families of Quadratic Surfaces Having Fixed Intersection with Two Hyperplanes,” Discrete Applied Mathematics, vol. 161, pp. 2778-2793, 2013. [PDF] [DOI] [Bibtex]
@Article{ BelGoePolRalTer13, author = {Belotti, P. and Goez, J.C. and Polik, I. and Ralphs, T.K. and Terlaky, T.}, doi = {10.1016/j.dam.2013.05.017}, journal = {Discrete Applied Mathematics}, pages = {2778--2793}, title = {{On Families of Quadratic Surfaces Having Fixed Intersection with Two Hyperplanes}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/Quadratic11.pdf} , volume = {161}, year = {2013} }
- M. V. Galati, T. K. Ralphs, and J. Wang, “Computational Experience with Generic Decomposition using the DIP Framework,” in Proceedings of RAMP 2012, 2012. [Software] [PDF] [Bibtex]
@InProceedings{ GalRalWan12, software = {https://projects.coin-or.org/Dip}, author = {Galati, M.V. and Ralphs, T.K. and Wang, J.}, booktitle = {Proceedings of RAMP 2012}, title = {{Computational Experience with Generic Decomposition using the DIP Framework}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/RAMP12.pdf}, year = {2012} }
- T. Koch, T. K. Ralphs, and Y. Shinano, “Could We Use a Million Cores to Solve an Integer Program?,” Mathematical Methods of Operations Research, vol. 76, pp. 67-93, 2012. [PDF] [DOI] [Bibtex]
@Article{ KocRalShi12, author = {Koch, T. and Ralphs, T.K. and Shinano, Y.}, doi = {10.1007/s00186-012-0390-9}, journal = {Mathematical Methods of Operations Research}, pages = {67--93}, title = {{Could We Use a Million Cores to Solve an Integer Program?}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/Million11.pdf} , volume = {76}, year = {2012} }
- T. Koch, T. Achterburg, E. Andersen, O. Bastert, T. Berthold, R. E. Bixby, E. Danna, G. Gamrath, A. Gleixner, S. Heinz, A. Lodi, H. Mittelmann, T. K. Ralphs, D. Salvagnin, D. Steffy, and K. Wolter, “MIPLIB 2010,” Mathematical Programming Computation, vol. 3, pp. 103-163, 2011. [Software] [PDF] [DOI] [Bibtex]
@Article{ KocAchAndBasBerBixDanGamGleHei.ea11, software = {http://miplib.zib.de/download/scriptversions/}, author = {Koch, T. and Achterburg, T. and Andersen, E. and Bastert, O. and Berthold, T. and Bixby, R.E. and Danna, E. and Gamrath, G. and Gleixner, A. and Heinz, S. and Lodi, A. and Mittelmann, H. and Ralphs, T.K. and Salvagnin, D. and Steffy, D. and Wolter, K.}, doi = {10.1007/s12532-011-0025-9}, journal = {Mathematical Programming Computation}, pages = {103--163}, title = {{MIPLIB 2010}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/miplib5.pdf}, volume = {3}, year = {2011} }
- A. Mahajan and T. K. Ralphs, “On the Complexity of Selecting Disjunctions in Integer Programming,” SIAM Journal on Optimization, vol. 20, iss. 5, pp. 2181-2198, 2010. [PDF] [DOI] [Bibtex]
@Article{ MahRal10, author = {Mahajan, A. and Ralphs, T.K.}, doi = {10.1137/080737587}, journal = {SIAM Journal on Optimization}, number = {5}, pages = {2181--2198}, title = {{On the Complexity of Selecting Disjunctions in Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/Branching08.pdf} , volume = {20}, year = {2010} }
- T. K. Ralphs and M. V. Galati, “Decomposition Methods,” in Encyclopedia of Operations Research and Management Science, J. Cochran, Ed., Wiley, 2010. [PDF] [DOI] [Bibtex]
@InCollection{ RalGal10, author = {Ralphs, T.K. and Galati, M.V.}, booktitle = {Encyclopedia of Operations Research and Management Science}, doi = {10.1002/9780470400531}, editor = {Cochran, J.}, publisher = {Wiley}, title = {{Decomposition Methods}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/Decomp-EOR10.pdf} , year = {2010} }
- M. Güzelsoy and T. K. Ralphs, “Integer Programming Duality,” in Encyclopedia of Operations Research and Management Science, J. Cochran, Ed., Wiley, 2010. [PDF] [DOI] [Bibtex]
@InCollection{ GuzRal10, author = {G{\"u}zelsoy, M. and Ralphs, T.K.}, booktitle = {Encyclopedia of Operations Research and Management Science}, doi = {10.1002/9780470400531}, editor = {{J. Cochran}}, publisher = {Wiley}, title = {{Integer Programming Duality}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/Duality-EOR10.pdf} , year = {2010} }
- S. DeNegre and T. K. Ralphs, “A Branch-and-Cut Algorithm for Bilevel Integer Programming,” in Proceedings of the Eleventh INFORMS Computing Society Meeting, 2009, pp. 65-78. [Software] [PDF] [DOI] [Bibtex]
@InProceedings{ DeNRal09, software = {https://github.com/tkralphs/MibS}, author = {DeNegre, S. and Ralphs, T.K.}, booktitle = {Proceedings of the Eleventh INFORMS Computing Society Meeting}, doi = {10.1007/978-0-387-88843-9_4}, pages = {65--78}, title = {{A Branch-and-Cut Algorithm for Bilevel Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BILEVEL08.pdf} , year = {2009} }
- A. Mahajan and T. K. Ralphs, “Experiments with Branching using General Disjunctions,” in Proceedings of the Eleventh INFORMS Computing Society Meeting, 2009, pp. 101-118. [PDF] [DOI] [Bibtex]
@InProceedings{ MahRal09, author = {Mahajan, A. and Ralphs, T.K.}, booktitle = {Proceedings of the Eleventh INFORMS Computing Society Meeting}, doi = {10.1007/978-0-387-88843-9_6}, pages = {101--118}, title = {{Experiments with Branching using General Disjunctions}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CompBranching08.pdf} , year = {2009} }
- Z. Akca, R. T. Berger, and T. K. Ralphs, “A Branch-and-Price Algorithm for Combined Location and Routing Problems Under Capacity Restrictions,” in Proceedings of the Eleventh INFORMS Computing Society Meeting, 2009, pp. 309-330. [PDF] [DOI] [Bibtex]
@InProceedings{ AkcBerRal09, author = {Akca, Z. and Berger, R.T. and Ralphs, T.K.}, booktitle = {Proceedings of the Eleventh INFORMS Computing Society Meeting}, doi = {10.1007/978-0-387-88843-9_16}, pages = {309--330}, title = {{A Branch-and-Price Algorithm for Combined Location and Routing Problems Under Capacity Restrictions}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/LRP08.pdf}, year = {2009} }
- Y. Xu, T. K. Ralphs, L. Ladányi, and M. J. Saltzman, “Computational Experience with a Software Framework for Parallel Integer Programming,” The INFORMS Journal on Computing, vol. 21, pp. 383-397, 2009. [Software] [PDF] [DOI] [Bibtex]
@Article{ XuRalLadSal09, software = {https://projects.coin-or.org/CHiPPS}, author = {Xu, Y. and Ralphs, T.K. and Lad{\'a}nyi, L. and Saltzman, M.J.}, doi = {10.1287/ijoc.1090.0347}, journal = {The INFORMS Journal on Computing}, pages = {383--397}, title = {{Computational Experience with a Software Framework for Parallel Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CHiPPS-Rev.pdf} , volume = {21}, year = {2009} }
- A. Lodi and T. K. Ralphs, “Bilevel Programming and Maximally Violated Valid Inequalities,” in Proceedings of the Cologne Twente Workshop on Graphs and Combinatorial Optimization, 2009, pp. 125-134. [PDF] [Bibtex]
@InProceedings{ LodRal09, author = {Lodi, A. and Ralphs, T.K.}, booktitle = {Proceedings of the Cologne Twente Workshop on Graphs and Combinatorial Optimization}, pages = {125--134}, title = {{Bilevel Programming and Maximally Violated Valid Inequalities}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CTW09.pdf}, year = {2009} }
- M. Güzelsoy and T. K. Ralphs, “Duality for Mixed-Integer Linear Programs,” International Journal of Operations Research, vol. 4, pp. 118-137, 2007. [PDF] [Bibtex]
@Article{ GuzRal07, author = {G{\"u}zelsoy, M. and Ralphs, T.K.}, journal = {International Journal of Operations Research}, pages = {118--137}, title = {{Duality for Mixed-Integer Linear Programs}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MILPD06.pdf}, volume = {4}, year = {2007} }
- T. K. Ralphs and M. V. Galati, “Decomposition and Dynamic Cut Generation in Integer Programming,” Mathematical Programming, vol. 106, pp. 261-285, 2006. [Software] [PDF] [DOI] [Bibtex]
@Article{ RalGal06, software = {https://projects.coin-or.org/}, author = {Ralphs, T.K. and Galati, M.V.}, doi = {10.1007/s10107-005-0606-3}, journal = {Mathematical Programming}, pages = {261--285}, title = {{Decomposition and Dynamic Cut Generation in Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/DECOMP.pdf}, volume = {106}, year = {2006} }
- T. K. Ralphs, “Parallel Branch and Cut,” in Parallel Combinatorial Optimization, E. Talbi, Ed., New York: Wiley, 2006, pp. 53-101. [Software] [PDF] [Bibtex]
@InCollection{ Ral06, address = {New York}, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K.}, booktitle = {Parallel Combinatorial Optimization}, editor = {{E. Talbi}}, pages = {53--101}, publisher = {Wiley}, title = {{Parallel Branch and Cut}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/PBandC.pdf}, year = {2006} }
- T. K. Ralphs, M. J. Saltzman, and M. M. Wiecek, “An Improved Algorithm for Biobjective Integer Programming,” Annals of Operations Research, vol. 147, pp. 43-70, 2006. [Software] [PDF] [DOI] [Bibtex]
@Article{ RalSalWie06, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Saltzman, M.J. and Wiecek, M.M.}, doi = {10.1007/s10479-006-0058-z}, journal = {Annals of Operations Research}, pages = {43--70}, title = {{An Improved Algorithm for Biobjective Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BICRIT2.pdf}, volume = {147}, year = {2006} }
- T. K. Ralphs and M. Güzelsoy, “Duality and Warm Starting in Integer Programming,” in The Proceedings of the 2006 NSF Design, Service, and Manufacturing Grantees and Research Conference, 2006. [Software] [PDF] [Bibtex]
@InProceedings{ RalGuz06, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and G{\"u}zelsoy, M.}, booktitle = {The Proceedings of the 2006 NSF Design, Service, and Manufacturing Grantees and Research Conference}, title = {{Duality and Warm Starting in Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/DMII06.pdf}, year = {2006} }
- T. K. Ralphs and M. V. Galati, “Decomposition in Integer Programming,” in Integer Programming: Theory and Practice, J. Karlof, Ed., CRC Press, 2005, pp. 57-110. [PDF] [Bibtex]
@InCollection{ RalGal05, author = {Ralphs, T.K. and Galati, M.V.}, booktitle = {Integer Programming: Theory and Practice}, editor = {Karlof, J}, pages = {57--110}, publisher = {CRC Press}, title = {{Decomposition in Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/DECOMP04.pdf} , year = {2005} }
- Y. Xu, T. K. Ralphs, L. Ladányi, and M. J. Saltzman, “ALPS: A Framework for Implementing Parallel Tree Search Algorithms,” in The Proceedings of the Ninth INFORMS Computing Society Conference, 2005, pp. 319-334. [Software] [PDF] [DOI] [Bibtex]
@InProceedings{ XuRalLadSal05, abstract = {ALPS is a framework for implementing and parallelizing tree search algorithms. It employs a number of features to improve scalability and is designed specifically to support the implementation of data intensive algorithms, in which large amounts of knowledge are generated and must be maintained and shared during the search. Implementing such algorithms in a scalable manner is challenging both because of storage requirements and because of communications overhead incurred in the sharing of data. In this abstract, we describe the design of ALPS and how the design addresses these challenges. We present two sample applications built with ALPS and preliminary computational results. {\textcopyright} 2005 Springer Science+Business Media, Inc.}, software = {https://projects.coin-or.org/CHiPPS}, author = {Xu, Y. and Ralphs, T.K. and Lad{\'a}nyi, L. and Saltzman, M.J.}, booktitle = {The Proceedings of the Ninth INFORMS Computing Society Conference}, doi = {10.1007/0-387-23529-9_21}, issn = {1387666X}, keywords = {Branch and bound,Integer programming,Parallel algorithm,Software}, pages = {319--334}, title = {{ALPS: A Framework for Implementing Parallel Tree Search Algorithms}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ALPS04.pdf}, volume = {29}, year = {2005} }
- J. T. Linderoth and T. K. Ralphs, “Noncommercial Software for Mixed-Integer Linear Programming,” in Integer Programming: Theory and Practice, J. Karlof, Ed., CRC Press, 2005, pp. 253-303. [PDF] [Bibtex]
@InCollection{ LinRal05, author = {Linderoth, J.T. and Ralphs, T.K.}, booktitle = {Integer Programming: Theory and Practice}, editor = {Karlof, J}, pages = {253--303}, publisher = {CRC Press}, title = {{Noncommercial Software for Mixed-Integer Linear Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MILP04.pdf}, year = {2005} }
- T. K. Ralphs and M. Güzelsoy, “The SYMPHONY Callable Library for Mixed Integer Programming,” in Proceedings of the Ninth INFORMS Computing Society Conference, 2005, pp. 61-76. [Software] [PDF] [DOI] [Bibtex]
@InProceedings{ RalGuz05, abstract = {SYMPHONY is a customizable, open-source library for solving mixed-integer linear programs (MILP) by branch, cut, and price. With its large assortment of parameter settings, user callback functions, and compile-time options, SYMPHONY can be configured as a generic MILP solver or an engine for solving difficult MILPs by means of a fully customized algorithm. SYMPHONY can run on a variety of architectures, including single-processor, distributed-memory parallel, and shared-memory parallel architectures under MS Windows, Linux, and other Unix operating systems. The latest version is implemented as a callable library that can be accessed either through calls to the native C application program interface, or through a C++ interface class derived from the COIN-OR Open Solver Interface. Among its new features are the ability to solve bicriteria MILPs, the ability to stop and warm start MILP computations after modifying parameters or problem data, the ability to create persistent cut pools, and the ability to perform rudimentary sensitivity analysis on MILPs. {\textcopyright} 2005 Springer Science+Business Media, Inc.}, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and G{\"u}zelsoy, M.}, booktitle = {Proceedings of the Ninth INFORMS Computing Society Conference}, doi = {10.1007/0-387-23529-9_5}, issn = {1387666X}, keywords = {Branch and bound,Branch and cut,Integer programming,Sensitivity analysis,Software}, pages = {61--76}, title = {{The SYMPHONY Callable Library for Mixed Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/SYMPHONY04.pdf} , year = {2005} }
- T. K. Ralphs, L. Ladányi, and M. J. Saltzman, “A Library Hierarchy for Implementing Scalable Parallel Search Algorithms,” Journal of Supercomputing, vol. 28, pp. 215-234, 2004. [Software] [PDF] [DOI] [Bibtex]
@Article{ RalLadSal04, software = {https://projects.coin-or.org/CHiPPS}, author = {Ralphs, T.K. and Lad{\'a}nyi, L. and Saltzman, M.J.}, doi = {10.1023/B:SUPE.0000020179.55383.ad}, journal = {Journal of Supercomputing}, pages = {215--234}, title = {{A Library Hierarchy for Implementing Scalable Parallel Search Algorithms}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/JSC02.pdf}, volume = {28}, year = {2004} }
- T. K. Ralphs, “Parallel Branch and Cut for Capacitated Vehicle Routing,” Parallel Computing, vol. 29, pp. 607-629, 2003. [Software] [PDF] [DOI] [Bibtex]
@Article{ Ral03, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K.}, doi = {10.1016/S0167-8191(03)00045-0}, journal = {Parallel Computing}, pages = {607--629}, title = {{Parallel Branch and Cut for Capacitated Vehicle Routing}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/PVRP.pdf}, volume = {29}, year = {2003} }
- T. K. Ralphs, L. Ladányi, and M. J. Saltzman, “Parallel Branch, Cut, and Price for Large-Scale Discrete Optimization,” Mathematical Programming, vol. 98, pp. 253-280, 2003. [Software] [PDF] [DOI] [Bibtex]
@Article{ RalLadSal03, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Lad{\'a}nyi, L. and Saltzman, M.J.}, doi = {10.1007/s10107-003-0404-8}, journal = {Mathematical Programming}, pages = {253--280}, title = {{Parallel Branch, Cut, and Price for Large-Scale Discrete Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/PBCP.pdf}, volume = {98}, year = {2003} }
- T. K. Ralphs, L. Kopman, W. R. Pulleyblank, and L. E. Trotter Jr., “On the Capacitated Vehicle Routing Problem,” Mathematical Programming, vol. 94, pp. 343-359, 2003. [Software] [PDF] [DOI] [Bibtex]
@Article{ RalKopPulTro-Jr03, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Kopman, L. and Pulleyblank, W.R. and Trotter Jr., L.E.}, doi = {10.1007/s10107-002-0323-0}, journal = {Mathematical Programming}, pages = {343--359}, title = {{On the Capacitated Vehicle Routing Problem}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/VRP.pdf}, volume = {94}, year = {2003} }
- L. Ladányi, T. K. Ralphs, and M. J. Saltzman, “Implementing Scalable Parallel Search Algorithms for Data-Intensive Applications,” in Proceedings of the International Conference on Computational Science, 2002, pp. 592-602. [Software] [PDF] [DOI] [Bibtex]
@InProceedings{ LadRalSal02, abstract = {Scalability is a critical issue in the design of parallel software for large-scale search problems. Previous research has not addressed this issue for data-intensive applications. We describe the design of a library for parallel search that focuses on efficient data and search tree management for such applications in distributed computing environments. {\textcopyright} 2002 Springer-Verlag Berlin Heidelberg.}, software = {https://projects.coin-or.org/CHiPPS}, author = {Lad{\'a}nyi, L. and Ralphs, T.K. and Saltzman, M.J.}, booktitle = {Proceedings of the International Conference on Computational Science}, doi = {10.1007/3-540-46043-8_60}, isbn = {3540435913}, issn = {03029743}, pages = {592--602}, title = {{Implementing Scalable Parallel Search Algorithms for Data-Intensive Applications}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ICCS02.pdf}, year = {2002} }
- L. Ladányi, T. K. Ralphs, and L. E. Trotter Jr., “Branch, Cut, and Price: Sequential and Parallel,” in Computational Combinatorial Optimization, D. Naddef and M. Juenger, Eds., Berlin: Springer, 2001, pp. 223-260. [PDF] [DOI] [Bibtex]
@InCollection{ LadRalTro-Jr01, address = {Berlin}, author = {Lad{\'a}nyi, L. and Ralphs, T.K. and Trotter Jr., L.E.}, booktitle = {Computational Combinatorial Optimization}, doi = {10.1007/3-540-45586-8_6}, editor = {Naddef, D and Juenger, M}, pages = {223--260}, publisher = {Springer}, title = {{Branch, Cut, and Price: Sequential and Parallel}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/LNCS.pdf}, year = {2001} }
- M. Esö, L. Ladányi, T. K. Ralphs, and L. E. Trotter Jr., “Fully Parallel Generic Branch-and-Cut Framework,” in Proceedings of the Eighth \SIAM\ Conference on Parallel Processing for Scientific Computing, 1997. [Software] [Bibtex]
@InProceedings{ EsoLadRalTro-Jr97, software = {https://projects.coin-or.org/SYMPHONY}, author = {Es{\"o}, M. and Lad{\'a}nyi, L. and Ralphs, T.K. and Trotter Jr., L.E.}, booktitle = {Proceedings of the Eighth {\{}SIAM{\}} Conference on Parallel Processing for Scientific Computing}, title = {{Fully Parallel Generic Branch-and-Cut Framework}}, year = {1997} }
- T. K. Ralphs, “On the Mixed Chinese Postman Problem,” Operations Research Letters, vol. 14, pp. 123-127, 1993. [PDF] [DOI] [Bibtex]
@Article{ Ral93, author = {Ralphs, T.K.}, doi = {10.1016/0167-6377(93)90021-8}, journal = {Operations Research Letters}, pages = {123--127}, title = {{On the Mixed Chinese Postman Problem}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MPP.pdf}, volume = {14}, year = {1993} }
Technical Reports and Publications In Review
- T. K. Ralphs, “A Unified Framework for Multistage Mixed Integer Linear Optimization,” COR@L Laboratory Report 20T-005, Lehigh University 2020. [PDF] [Bibtex]
@TechReport{ Ral20, author = {Ralphs, T.K.}, institution = {COR@L Laboratory Report 20T-005, Lehigh University}, title = {{A Unified Framework for Multistage Mixed Integer Linear Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MultistageFramework20.pdf} , year = {2020} }
- S. Coniglio and T. K. Ralphs, “Bound-optimal Cuts: On the Generation of Cuts Which Maximize the Bound Improvement,” Working Paper, COR@L Laboratory, Lehigh University 2020. [Bibtex]
@TechReport{ ConRal20, author = {Coniglio, S. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Bound-optimal Cuts: On the Generation of Cuts Which Maximize the Bound Improvement}}, year = {2020} }
- S. Bolusani and T. K. Ralphs, “A Framework for Generalized Benders’ Decomposition and Its Application to Multilevel Optimization,” COR@L Laboratory Report 20T-004, Lehigh University 2020. [PDF] [Bibtex]
@TechReport{ BolRal20, author = {Bolusani, S. and Ralphs, T.K.}, institution = {COR@L Laboratory Report 20T-004, Lehigh University}, title = {{A Framework for Generalized Benders' Decomposition and Its Application to Multilevel Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MultilevelBenders20.pdf} , year = {2020} }
- T. K. Ralphs, “Separation, Inverse Optimization, and Decomposition,” Working Paper, COR@L Laboratory, Lehigh University 2020. [PDF] [Bibtex]
@TechReport{ Ral20-1, author = {Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Separation, Inverse Optimization, and Decomposition}}, url = {http://coral.ie.lehigh.edu/~ted/files/talks/InversePrimalSeparation-PKU18.pdf} , year = {2020} }
- T. K. Ralphs, “Duality, Branch and Bound, and Parametric Valid Inequalities,” Working Paper, COR@L Laboratory, Lehigh University 2020. [PDF] [Bibtex]
@TechReport{ Ral20-2, author = {Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Duality, Branch and Bound, and Parametric Valid Inequalities}}, url = {http://coral.ie.lehigh.edu/~ted/files/talks/ParametricInequalities-INFORMS17.pdf} , year = {2020} }
- S. Tahernejad and T. K. Ralphs, “Valid Inequalities for Mixed Integer Bilevel Optimization,” Working Paper, COR@L Laboratory, Lehigh University 2020. [Software] [PDF] [Bibtex]
@TechReport{ TahRal20, software = {https://github.com/tkralphs/MibS}, author = {Tahernejad, S. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Valid Inequalities for Mixed Integer Bilevel Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/talks/BilevelCuts-IWOBIP18.pdf} , year = {2020} }
- A. Gleixner, G. Hendel, G. Gamrath, T. Achterberg, M. Bastubbe, T. Berthold, P. Christophel, K. Jarck, T. Koch, J. Linderoth, M. Luebbecke, H. D. Mittelmann, D. Ozyurt, T. K. Ralphs, Y. Shinano, and D. Salvagnin, “MIPLIB 2017: Data-Driven Compilation of the 6th Mixed-Integer Programming Library,” Zuse Institute Berlin 2019. [PDF] [Bibtex]
@TechReport{ GleHenGamAchBasBerChrJarKocLin.ea19, author = {Gleixner, Ambros and Hendel, Gregor and Gamrath, Gerald and Achterberg, Tobias and Bastubbe, Michael and Berthold, Timo and Christophel, Philipp and Jarck, Kati and Koch, Thorsten and Linderoth, Jeffrey and Luebbecke, Marco and Mittelmann, Hans D. and Ozyurt, Derya and Ralphs, Ted K. and Shinano, Yuji and Salvagnin, Domenico}, institution = {Zuse Institute Berlin}, title = {{MIPLIB 2017: Data-Driven Compilation of the 6th Mixed-Integer Programming Library}}, url = {http://www.optimization-online.org/DB{\_}FILE/2019/07/7285.pdf} , year = {2019} }
- S. J. Maher, T. K. Ralphs, and Y. Shinano, “Assessing the Effectiveness of (Parallel) Branch-and-Bound Algorithms,” COR@L Technical Report 19T-017 2019. [PDF] [Bibtex]
@TechReport{ MahRalShi19, author = {Maher, S.J. and Ralphs, T.K. and Shinano, Y.}, institution = {COR@L Technical Report 19T-017}, title = {{Assessing the Effectiveness of (Parallel) Branch-and-Bound Algorithms}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ParallelAssessment19.pdf} , year = {2019} }
- M. Walter and T. K. Ralphs, “Algorithms for Inverse Mixed Integer Programming,” Working Paper, COR@L Laboratory, Lehigh University 2018. [Bibtex]
@TechReport{ WalRal18, author = {Walter, M. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Algorithms for Inverse Mixed Integer Programming}}, year = {2018} }
- A. Bulut and T. K. Ralphs, “Complexity for Mathematical Programs,” Working Paper, COR@L Laboratory, Lehigh University 2017. [PDF] [Bibtex]
@TechReport{ BulRal17, author = {Bulut, A. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Complexity for Mathematical Programs}}, url = {http://coral.ie.lehigh.edu/~ted/files/talks/MIP12.pdf}, year = {2017} }
- M. V. Galati and T. K. Ralphs, “DIP: A Framework for Decomposition in Integer Programming,” Working Paper, COR@L Laboratory, Lehigh University 2017. [Software] [PDF] [Bibtex]
@TechReport{ GalRal17, software = {https://projects.coin-or.org/Dip}, author = {Galati, M.V. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{DIP: A Framework for Decomposition in Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/talks/DecompCSIRO11.pdf} , year = {2017} }
- M. E. Pfetsch and T. K. Ralphs, “Towards More "Scientific" Computations in Mathematical Optimization,” Working Paper, COR@L Laboratory, Lehigh University 2017. [Bibtex]
@TechReport{ PfeRal17, author = {Pfetsch, M.E. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Towards More "Scientific" Computations in Mathematical Optimization}}, year = {2017} }
- A. Bulut and T. K. Ralphs, “DisCO: An Open Source Solver for Discrete Conic Optimization,” Working Paper, COR@L Laboratory, Lehigh University 2017. [Software] [PDF] [Bibtex]
@TechReport{ BulRal17-1, software = {https://github.com/aykutbulut/DisCO}, author = {Bulut, A. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{DisCO: An Open Source Solver for Discrete Conic Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/talks/DisCO-INFORMS17.pdf} , year = {2017} }
- S. T. DeNegre and T. K. Ralphs, “Computational Experience Solving Mixed Integer Interdiction Problems,” Working Paper, COR@L Laboratory, Lehigh University 2017. [Bibtex]
@TechReport{ DeNRal17, author = {DeNegre, S.T. and Ralphs, T.K.}, institution = {Working Paper, COR@L Laboratory, Lehigh University}, title = {{Computational Experience Solving Mixed Integer Interdiction Problems}}, year = {2017} }
- A. Bulut and T. K. Ralphs, “On the Complexity of Inverse Mixed Integer Linear Optimization,” COR@L Laboratory Report 15T-001-R3, Lehigh University 2015. [Software] [PDF] [Bibtex]
@TechReport{ BulRal15, software = {https://github.com/tkralphs/CuPPy}, author = {Bulut, A. and Ralphs, T.K.}, institution = {COR@L Laboratory Report 15T-001-R3, Lehigh University}, title = {{On the Complexity of Inverse Mixed Integer Linear Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/InverseMILP15.pdf} , year = {2015} }
- T. K. Ralphs, “Data Science and Analytics,” Industrial and Systems Engineering Report 15T-009, Lehigh University 2015. [PDF] [Bibtex]
@TechReport{ Ral15, author = {Ralphs, T.K.}, institution = {Industrial and Systems Engineering Report 15T-009, Lehigh University}, title = {{Data Science and Analytics}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/dataScience.pdf} , year = {2015} }
- A. Hassanzadeh and T. K. Ralphs, “A Generalization of Benders’ Algorithm for Two-Stage Stochastic Optimization Problems with Mixed Integer Recourse,” COR@L Laboratory Report 14T-005, Lehigh University 2014. [Software] [PDF] [Bibtex]
@TechReport{ HasRal14, software = {https://projects.coin-or.org/SYMPHONY}, author = {Hassanzadeh, A. and Ralphs, T.K.}, institution = {COR@L Laboratory Report 14T-005, Lehigh University}, title = {{A Generalization of Benders' Algorithm for Two-Stage Stochastic Optimization Problems with Mixed Integer Recourse}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/SMILPGenBenders14.pdf} , year = {2014} }
- A. Hassanzadeh and T. K. Ralphs, “On the Value Function of a Mixed Integer Linear Optimization Problem and an Algorithm for Its Construction,” COR@L Laboratory Report 14T-004, Lehigh University 2014. [Software] [PDF] [Bibtex]
@TechReport{ HasRal14-1, software = {https://github.com/tkralphs/ValueFunction}, author = {Hassanzadeh, A. and Ralphs, T.K.}, institution = {COR@L Laboratory Report 14T-004, Lehigh University}, title = {{On the Value Function of a Mixed Integer Linear Optimization Problem and an Algorithm for Its Construction}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MILPValueFunction14.pdf} , year = {2014} }
- T. K. Ralphs, M. Guzelsoy, and A. Mahajan, “SYMPHONY Version 5.6 User’s Manual,” COR@L Laboratory, Lehigh University 2014. [Software] [PDF] [Bibtex]
@TechReport{ RalGuzMah14, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Guzelsoy, M. and Mahajan, A.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.6 User's Manual}}, url = {https://coin-or.github.io/SYMPHONY/doc/SYMPHONY-5.6.17-Manual.pdf} , year = {2014} }
- T. K. Ralphs, M. Güzelsoy, and A. Mahajan, “SYMPHONY Version 5.5 User’s Manual,” COR@L Laboratory, Lehigh University 2013. [Software] [PDF] [Bibtex]
@TechReport{ RalGuzMah13, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and G{\"u}zelsoy, M. and Mahajan, A.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.5 User's Manual}}, url = {http://www.coin-or.org/SYMPHONY/doc/SYMPHONY-5.5.0-Manual.pdf} , year = {2013} }
- K. L. Hoffman and T. K. Ralphs, “Integer and Combinatorial Optimization,” 2013. [PDF] [DOI] [Bibtex]
@TechReport{ HofRal13, author = {Hoffman, K.L. and Ralphs, T.K.}, booktitle = {Encyclopedia of Operations Research and Management Science}, doi = {10.1007/978-1-4419-1153-7_129}, pages = {771--783}, publisher = {Springer}, title = {{Integer and Combinatorial Optimization}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ICO-EORMS11.pdf} , year = {2013} }
- T. K. Ralphs, M. Güzelsoy, and A. Mahajan, “SYMPHONY Version 5.4 User’s Manual,” COR@L Laboratory, Lehigh University 2011. [Software] [PDF] [Bibtex]
@TechReport{ RalGuzMah11-1, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and G{\"u}zelsoy, M. and Mahajan, A.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.4 User's Manual}}, url = {http://www.coin-or.org/SYMPHONY/doc/SYMPHONY-5.4.0-Manual.pdf} , year = {2011} }
- T. K. Ralphs, M. Güzelsoy, and A. Mahajan, “SYMPHONY Version 5.3 User’s Manual,” COR@L Laboratory, Lehigh University 2011. [Software] [PDF] [Bibtex]
@TechReport{ RalGuzMah11, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and G{\"u}zelsoy, M. and Mahajan, A.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.3 User's Manual}}, url = {http://www.coin-or.org/SYMPHONY/doc/SYMPHONY-5.3.4-Manual.pdf} , year = {2011} }
- A. Lodi, T. K. Ralphs, F. Rossi, and S. Smriglio, “Interdiction Branching,” COR@L Technical Report 11T-012-R2 2011. [Software] [PDF] [Bibtex]
@TechReport{ LodRalRosSmr11, software = {https://github.com/tkralphs/InterdictionBranch}, author = {Lodi, A. and Ralphs, T.K. and Rossi, F. and Smriglio, S.}, institution = {COR@L Technical Report 11T-012-R2}, title = {{Interdiction Branching}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BilevelBranching.pdf} , year = {2011} }
- M. Güzelsoy and T. K. Ralphs, “Warm-starting for Real-time Vehicle Routing,” COR@L Laboratory, Lehigh University 2011. [Software] [Bibtex]
@TechReport{ GuzRal11, software = {https://projects.coin-or.org/SYMPHONY}, author = {G{\"u}zelsoy, M. and Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh University}, title = {{Warm-starting for Real-time Vehicle Routing}}, year = {2011} }
- Z. Akca, R. T. Berger, and T. K. Ralphs, “Solution Methods for the Multi-trip Elementary Shortest Path Problem with Resource Constraints,” COR@L Laboratory, Lehigh University 2010. available by request. [PDF] [Bibtex]
@TechReport{ AkcBerRal10, annote = {available by request}, author = {Akca, Z. and Berger, R.T. and Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh University}, title = {{Solution Methods for the Multi-trip Elementary Shortest Path Problem with Resource Constraints}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/MESPPRC10.pdf} , year = {2010} }
- T. K. Ralphs, A. Mahajan, and M. Güzelsoy, “SYMPHONY Version 5.2 User’s Manual,” COR@L Laboratory, Lehigh University 2010. [Software] [PDF] [Bibtex]
@TechReport{ RalMahGuz10, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Mahajan, A. and G{\"u}zelsoy, M.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.2 User's Manual}}, url = {http://www.coin-or.org/SYMPHONY/doc/SYMPHONY-5.2.3-Manual.pdf} , year = {2010} }
- M. Güzelsoy and T. K. Ralphs, “The Value Function of a Mixed-integer Linear Program with a Single Constraint,” COR@L Laboratory, Lehigh University 2008. [PDF] [Bibtex]
@TechReport{ GuzRal08, author = {G{\"u}zelsoy, M. and Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh University}, title = {{The Value Function of a Mixed-integer Linear Program with a Single Constraint}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ValueFunction.pdf} , year = {2008} }
- T. K. Ralphs, “SYMPHONY Version 5.1 User’s Manual,” COR@L Laboratory, Lehigh University 2008. [Software] [PDF] [Bibtex]
@TechReport{ Ral08, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.1 User's Manual}}, url = {http://www.coin-or.org/SYMPHONY/SYMPHONY-5.1.8-Manual.pdf} , year = {2008} }
- Z. Akca, R. T. Berger, and T. K. Ralphs, “Modeling and Solving Location, Routing, and Scheduling Problems,” COR@L Laboratory Report 08T-009, Lehigh University 2008. [PDF] [Bibtex]
@TechReport{ AkcBerRal08, author = {Akca, Z. and Berger, R.T. and Ralphs, T.K.}, institution = {COR@L Laboratory Report 08T-009, Lehigh University}, title = {{Modeling and Solving Location, Routing, and Scheduling Problems}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/LRSP08.pdf}, year = {2008} }
- O. Osaltyn, B. Hunsaker, and T. K. Ralphs, “Visualizing Branch-and-Bound Algorithms,” COR@L Laboratory, Lehigh Univesity 2007. [Software] [PDF] [Bibtex]
@TechReport{ OsaHunRal07, software = {http://github.com/coin-or/GrUMPy}, author = {Osaltyn, O. and Hunsaker, B. and Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh Univesity}, title = {{Visualizing Branch-and-Bound Algorithms}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BBVis.pdf}, year = {2007} }
- Y. Xu, T. K. Ralphs, L. Ladányi, and M. J. Saltzman, “Computational Experience with a Framework for Parallel Integer Programming,” COR@L Laboratory Report , Lehigh University 2007. [Software] [PDF] [Bibtex]
@TechReport{ XuRalLadSal07, software = {https://projects.coin-or.org/CHiPPS}, author = {Xu, Y. and Ralphs, T.K. and Lad{\'a}nyi, L. and Saltzman, M.J.}, institution = {COR@L Laboratory Report , Lehigh University}, title = {{Computational Experience with a Framework for Parallel Integer Programming}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CHiPPS.pdf}, year = {2007} }
- T. K. Ralphs and M. Güzelsoy, “Duality, Warm Starting, and Sensitivity Analysis in Integer Programming,” COR@L Laboratory Report 04T-022, Lehigh University 2004. Available by request. [PDF] [Bibtex]
@TechReport{ RalGuz04, annote = {Available by request}, author = {Ralphs, T.K. and G{\"u}zelsoy, M.}, institution = {COR@L Laboratory Report 04T-022, Lehigh University}, title = {{Duality, Warm Starting, and Sensitivity Analysis in Integer Programming}}, url = {http://ise.lehigh.edu/sites/ise.lehigh.edu/files/04t{\_}022.pdf} , year = {2004} }
- T. K. Ralphs, M. J. Saltzman, and M. M. Wiecek, “An Improved Algorithm for Biobjective Integer Programming and Its Application to Network Routing Problems,” COR@L Laboratory Report 04T-004, Lehigh University 2004. [Software] [PDF] [Bibtex]
@TechReport{ RalSalWie04, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Saltzman, M.J. and Wiecek, M.M.}, institution = {COR@L Laboratory Report 04T-004, Lehigh University}, title = {{An Improved Algorithm for Biobjective Integer Programming and Its Application to Network Routing Problems}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BICRIT.pdf}, year = {2004} }
- T. K. Ralphs, “SYMPHONY Version 5.0 User’s Manual,” COR@L Laboratory, Lehigh University, Technical Report , 2004. [Software] [Bibtex]
@TechReport{ Ral04, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 5.0 User's Manual}}, type = {Technical Report}, year = {2004} }
- T. K. Ralphs, “SYMPHONY Version 4.0 User’s Manual,” COR@L Laboratory, Lehigh University, Technical Report , 2003. [Software] [Bibtex]
@TechReport{ Ral03-1, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K.}, institution = {COR@L Laboratory, Lehigh University}, title = {{SYMPHONY Version 4.0 User's Manual}}, type = {Technical Report}, year = {2003} }
- T. K. Ralphs and L. Ladányi, “COIN/BCP User’s Manual,” COR@L Laboratory, Lehigh University 2001. [Software] [PDF] [Bibtex]
@TechReport{ RalLad01, software = {http://projects.coin-or.org/Bcp}, author = {Ralphs, T.K. and Lad{\'a}nyi, L.}, institution = {COR@L Laboratory, Lehigh University}, title = {{COIN/BCP User's Manual}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/BCP-Manual.pdf} , year = {2001} }
- T. K. Ralphs and J. C. Hartman, “Capacitated Network Routing (A Preliminary Progress Report),” COR@L Laboratory Report 01W-009, Lehigh University 2001. [Software] [PDF] [Bibtex]
@TechReport{ RalHar01, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Hartman, J.C.}, institution = {COR@L Laboratory Report 01W-009, Lehigh University}, title = {{Capacitated Network Routing (A Preliminary Progress Report)}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/CNRP.pdf}, year = {2001} }
- T. K. Ralphs, L. Ladányi, and M. J. Saltzman, “A Library Hierarchy for Implementing Scalable Parallel Search Algorithms,” Industrial and Systems Engineering, Lehigh University 2001. [Software] [PDF] [Bibtex]
@TechReport{ RalLadSal01, software = {https://projects.coin-or.org/CHiPPS}, author = {Ralphs, T.K. and Lad{\'a}nyi, L. and Saltzman, M.J.}, institution = {Industrial and Systems Engineering, Lehigh University}, title = {{A Library Hierarchy for Implementing Scalable Parallel Search Algorithms}}, url = {http://coral.ie.lehigh.edu/~ted/files/papers/ALPS.pdf}, year = {2001} }
- T. K. Ralphs and L. Ladányi, “SYMPHONY: A Parallel Framework for Branch, Cut, and Price,” Rice University 2000. [Software] [Bibtex]
@TechReport{ RalLad00, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K. and Lad{\'a}nyi, L.}, institution = {Rice University}, title = {{SYMPHONY: A Parallel Framework for Branch, Cut, and Price}}, year = {2000} }
- T. K. Ralphs, “Parallel Branch and Cut for Vehicle Routing,” PhD Thesis, 1995. [Software] [Bibtex]
@PhDThesis{ Ral95, software = {https://projects.coin-or.org/SYMPHONY}, author = {Ralphs, T.K.}, month = {may}, school = {Cornell University}, title = {{Parallel Branch and Cut for Vehicle Routing}}, year = {1995} }
Software
- SYMPHONY: Single- or Multi-Process Optimization over Networks
An open-source, generic MILP solver, callable library, and extensible framework for implementing customized MILP solvers, SYMPHONY can be built in various sequential and parallel configurations for either distributed or shared memory architectures. SYMPHONY has a number of advanced capabilities stemming from the research projects discussed above, including the ability to solve multi-objective MILPs, the ability to warm start its solution procedure, and the ability to perform basic sensitivity analyses. SYMPHONY has an active user community and has been deployed in a variety of application areas, including computational biology, wireless telecommunications, supply chain management, transportation services, and air transportation. It can be used “out of the box” as a solver for generic mixed-integer linear programs or customized for a particular application through the use of numerous callback functions. - CHiPPS: The COIN High Performance Parallel Search Framework
This C++ class library and framework for implementing parallel search algorithms for large-scale, data-intensive applications consist of three layers. - ALPS: Abstract Library for Parallel Search
ALPS provides the base infrastructure for implementing a variety of search algorithms, such as branch and bound or constraint logic programming. Two prototype solvers, a vanilla branch-and-cut solver and a knapsack problem solver, have been derived from ALPS to demonstrate its use. - BiCePS: Branch, Constrain, and Price Software
Built on top of ALPS, BiCePS provides the data layer for implementing relaxation-based optimization algorithms, such as LP-based branch and bound. Scalability is maintained through the use of compact data structures for storage and communication of problem data. - BLIS: BiCePS Linear Integer Solver
This C++ class library is a concretization of BiCePS for the case of mixed-integer linear programming based on LP relaxation. From BLIS, one can easily derive custom solver applications. A number of such applications have already been developed, including a solver for various types of routing problems and a solver for mixed integer bilevel programs. - DIP
A software framework for implementing bounding methods for integer programs based on the integration of traditional decomposition methods with polyhedral methods. The framework has been integrated with CHiPPS to provide a complete solver framework. - GiMPy
This package began as a tool for visualizing various graph algorithms that I used in both ISE 172 and ISE 411. It has now been expanded out into a full-featured graph class that is useful as a research code due to its clarity of implementation and display capabilities. It is the basis for the GrUMPy project, which is a class for visualizing mathematical programming algorithms, such as branch and bound and the cutting plane method. - GruMPy
GruMPy is based on an earlier project called the Branch-and-Bound Analysis Kit (BAK), which was a tool for visualizing and monitoring the progress of branch-and-bound algorithms. It has now been re-implemented on top of GiMPy to take advantage of the capabilities of that class. - CuPPy
This package is a collection of implementations of cutting plane algorithms written in Python. It is intended both as a tool for use in the classroom in teaching discrete optimization and as a research tool. It includes some experimental methods for generating and visualizing some new classes of cutting planes not yet described in the literature. - BLImPy
BLIMPy is a collection of basic list data structures, such as the linked list that I use in ISE 172 and is also used in GiMPy. - COLA
A software project being developed as part a recently awarded NSF grant on conic Optimization. It is a solver for second order cone optimization problems that uses outer approximation of the second order cones. - DietCOLA
A solver for second order cone optimization problems that have integrality restrictions on some of the variables. DisCO is built on top of the CHiPPS tree search framework and is a proof-of-concept for the development of DisCO (see below). It solves the SOCPs with COLA. - DisCO
A solver for second order cone optimization problems that have integrality restrictions on some of the variables. It is a generalization of the BLIS solver from CHiPPs and replaces the simplex-based LP solver for solving the continuous relaxation problems there with a more general conic solver. - OSI-Conic
A generic solver API for conic optimization solvers that is used to provide an interface to various solvers that can be used to solve the continuous relaxations required in DisCO. - CGL-Conic
A library of constraint generators for discrete conic optimization problems the be used within the DisCO framework. - MibS: Mixed Integer Bilevel Solver
A software package for solving mixed integer bilevel programs. Such programs arise in the analysis of hierarchical decision systems with multiple, independent decision-makers whose interests are not necessarily aligned. The solver implements a rudimentary branch-and-cut algorithm for solving integer bilevel linear programs that extends existing techniques for standard integer linear programs. It uses cutting plane techniques to produce improved bounds, does not require specialized branching strategies, and can be implemented in a straightforward way using only linear solvers. Our implementation is built using software components available in the COIN-OR software repository. - COIN-OR Optimization Suite
I maintain a build harness and installers for the interoperable suite of tools available in COIN for solving optimization problems. This includes a broad range of solvers and the suite is perhaps the most capable such suite available overall, including commercial offerings. It is very widely used and has been embedded in or can be accessed from all the top modeling and analysis
environments, including the Excel and OpenOffice spreadsheets, Matlab, Sage, R, Python, and all major modeling languages.
Plenaries, Keynotes, Tutorials, and Short Courses
- T.K. Ralphs, Multilevel and Multistage Optimization (Short Course), University of Erlangen, Erlangen, Germany, March 2017 (Slides)
- T.K. Ralphs, Multilevel and Multistage Optimization (Short Course), Zuse Institute Berlin, Berlin, Germany, December 2016 (Slides)
- T.K. Ralphs, Computational Integer Programming (Short Course), International Workshop on Modern Optimization and Applications, Beijing, China, June 2016 (Slides)
- T.K. Ralphs, S. DeNegre, M. Guzelsoy, and A. Hassanzadeh, and S. Tahernajad Multistage Discrete Optimization (Tutorial), INFORMS Optimization Society Conference, Princeton, NJ, March 2016
- T.K. Ralphs, S. DeNegre, M. Guzelsoy, and A. Hassanzadeh, and S. Tahernajad Multistage Discrete Optimization (Plenary), First International Workshop on Bilevel Programming, Monterrey, Mexico, March 2016 (PDF)
- T.K. Ralphs, Multilevel and Multistage Optimization (Short Course), IIT Bombay, Mumbai, India, December 2015 (Slides)
- T.K. Ralphs, COIN Fest 2015: Workshop on Modeling and the COIN-OR Optimization Suite (Full-day Tutorial), INFORMS Computing Society Conference, Richmond, Virginia, January 2015. (Slides
- T.K. Ralphs, Accessible Analytics: Openness and Operations Research (Keynote Address), South African Operational Research Society Conference 2014, Parys, South Africa, September 2014.
- T.K. Ralphs, An Introduction to the COIN-OR Optimization Suite (Tutorial), South African Operational Research Society Conference 2014, Parys, South Africa, September 2014 (Slides)
- T.K. Ralphs Tools for Modeling Optimization Problems (Tutorial), North-West University, PUK Campus, Potchefstroom, South Africa, June 2013 (Slides).
- T.K. Ralphs An Introduction to the COIN-OR Optimization Suite: Open Source Tools for Building and Solving Optimization Models (Tutorial), Optimization Days, Montreal, May 2013 (PDF)
- T.K. Ralphs, et. al., Decomposition Methods for Discrete Optimization (Tutorial), INFORMS Computing Society Biannual Meeting, Santa Fe, NM, January 2013 (PDF).
- T.K. Ralphs, Computational Integer Programming (Short Course), Universidad de los Andes, August, 2010 (a href=/~ted/teaching/mip”>Course Page).
- T.K. Ralphs and M. Guzelsoy, A Mini-Tutorial on the SYMPHONY Callable Library for Mixed-Integer Linear Programming, The Ninth INFORMS Computing Society Conference, Annapolis, MD, January 2005 (PS PDF).
- T.K. Ralphs, L. Ladányi, and M.J. Saltzman , Tutorial: COIN-OR: Software Tools for Implementing Custom Solvers, the Institute for Operations Research and Management Science Annual Conference, Atlanta, GA, October 2003. (PS PDF).
- T.K. Ralphs, L. Ladányi, and M.J. Saltzman, Software Tools for Implementing Branch, Cut, and Price Algorithms (Tutorial), The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002 . (PS PDF).
- L. Ladányi and T.K. Ralphs, Open-source Tool Kit for Implementing Branch, Cut, and Price Algorithms (Tutorial), The Institute for Operations Research and Management Science Annual Conference, Miami, FL, November 2001.
- T.K. Ralphs and L. Ladányi, SYMPHONY: A Framework for Parallel Branch and Cut (Tutorial), DONET Spring School on Computation Combinatorial Optimization, Saarbrucken, Germany, May 2000 (PS PDF).
Conference Presentations
- T.K. Ralphs and S. Bolusani, Parametric Valid Inequalities, INFORMS Annual Meeting, Seattle, WA, October 2019 (PDF)
- T.K. Ralphs, S. Bolusani and S. Tahernejad, Multistage/Multilevel Discrete Optimization, International Conference on Stochastic Programming, Trondheim, Norway, July 2019 (PDF)
- T.K. Ralphs, Duality in Integer Linear Programming, Joint Mathematics Meetings, Baltimore, MD, January 2019 (PDF)
- T.K. Ralphs, S.J. Maher, and Y. Shinano, Assessing Performance of Parallel MILP Solvers, UG Workshop, Berlin, Germany, January 2019 (PDF)
- T.K. Ralphs, Separation, Inverse Optimization, and Decomposition: Connecting the Dots, 23rd Workshop on Combinatorial Optimization, Aussois, France, January 2019 (PDF)
- S. Tahernejad and T.K. Ralphs, Two-stage Mixed-integer Stochastic Bilevel Optimization Problems, INFORMS Annual Meeting, Phoenix, AZ, November 2018
- S. Bolusani, F. Qiu, T.K. Ralphs, A. Botterud, and K. Kim, Warm Starting for Security Constrained Deterministic Unit Commitment, INFORMS Annual Meeting, Phoenix, AZ, November 2018
- T.K. Ralphs, Introduction to COIN-OR and the Optimization Suite, COIN fORgery: Developing Open Source Tools for Operations Research, Institute for Mathematics and Its Applications, Minneapolis, MN, October 2018 (PDF)
- T.K. Ralphs, Introduction to Project Management in COIN-OR, COIN fORgery: Developing Open Source Tools for Operations Research, Institute for Mathematics and Its Applications, Minneapolis, MN, October 2018 (PDF)
- T.K. Ralphs, Introduction to Build and Test in COIN-OR, COIN fORgery: Developing Open Source Tools for Operations Research, Institute for Mathematics and Its Applications, Minneapolis, MN, October 2018 (PDF)
- S. Bolusani and T.K. Ralphs, Generalized Benders’ Algorithm for Mixed Integer Bilevel Linear Optimization, MOPTA 2018, Bethlehem, PA, August 2018 (PDF)
- T.K. Ralphs, Parallel Solution of Mixed Integer Linear Programs, New Computing-driven Opportunities for Optimization, Wuyishan, Fujian, China, August 2018 (PDF)
- T.K. Ralphs, Separation, Inverse Optimization, and Decomposition: Some Observations, Peking University Workshop on Optimization Theory and Methods, Beijing, China, August 2018 (PDF)
- S. Bolusani and T.K. Ralphs, Generalized Benders’ Algorithm for Mixed Integer Bilevel Linear Optimization, Second International Workshop of Bilvel Programming, Lille, France, June 2018
- S. Tahernejad, T.K. Ralphs, Valid Inequalities for Mixed Integer Bilevel Linear Optimization (poster), Second International Workshop of Bilvel Programming, Lille, France, June 2018 (PDF)
- S. Tahernejad, T.K. Ralphs, Valid Inequalities for Mixed Integer Bilevel Linear Optimization (poster), Mixed Integer Programming Workshop, Clemson, SC, June 2018 (PDF)
- T.K. Ralphs, S.J. Maher, and Y. Shinano, Assessing Performance of Parallel MILP Solvers, International Symposium on Mathematical Programming, Bordeaux, France, July 2018 (PDF)
- T.K. Ralphs, S.J. Maher, and Y. Shinano, Assessing Performance of Parallel MILP Solvers, SIAM Conference on Parallel Processing for Scientific Computing, Tokyo, Japan, March 2018
- T.K. Ralphs, Multilevel Optimization and Game Theory: Applications and Algorithms, Tsinghua University, Beijing, China, March 2018
and Portfolio Models, MINLP 2014, Carnegie Mellon University, Pittsburgh, PA, June 2014.
Seminar Presentations
- T.K. Ralphs, Multilevel Optimization and Game Theory: Applications and Algorithms, Tsinghua University, Beijing, China, March 2018
- T.K. Ralphs, Algorithms: Why and How, Guest Lecture, Introduction to Operations Research, Cal Poly, San Luis Obispo, CA, March 2017 (PDF)
- T.K. Ralphs, S. DeNegre, M. Guzelsoy, and A. Hassanzadeh, and S. Tahernajad, Duality, Multilevel Optimization, and Game Theory: Algorithms and Applications, Virginia Tech, Blacksburg, VA, February 2017 (PDF)
- T.K. Ralphs, S. DeNegre, M. Guzelsoy, and A. Hassanzadeh, and S. Tahernajad, Duality, Multilevel Optimization, and Game Theory: Algorithms and Applications, Norwegian School of Economics, Bergen, Norway, September 2016 (PDF)
- T.K.R., Duality and Warm-starting in MILP, Zuse Institute Berlin, Berlin, Germany, September 2016 (PDF)
- T.K. Ralphs, A. Bulut, S. DeNegre, M. Guzelsoy, A. Hassanzadeh, Multistage Integer Programming: Algorithms and Complexity, University of Houston, March 2014.
- T.K. Ralphs, A. Bulut, S. DeNegre, M. Guzelsoy, A. Hassanzadeh, Multilevel and Multistage Integer Programming: Algorithms and Complexity, Oakland University, November 2013.
- T.K. Ralphs, A. Bulut, S. DeNegre, M. Guzelsoy, A. Hassanzadeh, Multilevel and Multistage Integer Programming: Algorithms and Complexity, University of Florida, October 2013.
- T.K. Ralphs, A. Bulut, S. DeNegre, M. Guzelsoy, A. Hassanzadeh, Multilevel Integer Programming, The Polynomial Time Hierarchy, and Parallel Computing, Penn State University, March 2013
- T.K. Ralphs, A. Bulut, A. Lodi, F. Rossi, S. Smriglio, and G. Woeginger, Complexity and Multilevel Optimization, University of Kyoto, Kyoto, Japan, September 2012.
- T.K. Ralphs, A. Bulut, A. Lodi, F. Rossi, S. Smriglio, and G. Woeginger, Complexity and Multilevel Optimization, Chuo University, Tokyo, Japan, September 2012.
- T.K. Ralphs, M. Galati, and J. Wang, DIP with CHiPPS: Decomposition in Integer Linear Programming, CSIRO, Melbourne, Australia, December 2011 (PDF).
- T.K. Ralphs Making Molehills out of Mountains: A Guided Tour of Discrete Optimization, CSIRO, Melbourne, Australia, December 2011 (PDF).
- T.K. Ralphs, M. Galati, and J. Wang, DIP with CHiPPS: Decomposition in Integer Linear Programming, University of Michigan, Ann Arbor, MI, November 2011 (PDF).
- T.K. Ralphs and M. Galati, DIP with CHiPPS: Decomposition in Integer Linear Programming, ExxonMobil Research, Annandale, NJ, October 2011 (PDF).
- T.K. Ralphs, S. DeNegre, and M. Guzelsoy, Bilevel Integer Linear Programming, University of Edinburgh, Edinburgh, UK, May 2011 (PDF).
- T.K. Ralphs and M. Galati, Decomposition in Integer Linear Programming, Cornell University, Ithaca, NY, March 2011 (PDF).
- T.K. Ralphs, S. DeNegre, and M. Guzelsoy, Bilevel Integer Linear Programming, Northwestern University, Chicago, IL, January 2011 (PDF).
- T.K. Ralphs, S. DeNegre, M. Guzelsoy, A. Lodi, F. Rossi, and S. Smriglio, Bilevel Integer Programming, University of Pittsburgh, Pittsburgh, PA, October 2010 (PDF).
- T.K. Ralphs and M. Galati, DIP with ChiPPS: Decomposition Methods for Integer Linear Programming, University of Bordeaux, Bordeaux, France, June 2010 (PDF).
- T.K. Ralphs and M. Galati, DIP with ChiPPS: Decomposition Methods for Integer Linear Programming, University of Edinburgh, Edinburgh, Scotland, June 2010.
- T.K. Ralphs, Introduction to COIN-OR Tools for Optimization, COR@L Seminar, Lehigh University, January 2010 (PDF).
- T.K. Ralphs and M. Guzelsoy, Duality in Mixed Integer Linear Programming, University of Newcastle, Newcastle, Australia, May 2009 (PDF).
- T.K. Ralphs and M. Guzelsoy, Duality in Mixed Integer Linear Programming, Monash University, Melbourne, Australia, April 2009.
- T.K. Ralphs and S. Denegre, Bilevel Integer Linear Programming, University of Melbourne, Australia, April 2009.
- A. Mahajan and T.K. Ralphs, In Search of Optimal Disjunctions in Mixed Integer Programming, Monash University, Melbourne, Australia, April 2009.
- T.K. Ralphs and M. Galati, A Framework for Decomposition in Integer Programming, Monash University, Melbourne, Australia, March 2009 (PDF).
- T.K. Ralphs, Y. Xu, L. Ladanyi, and M.Saltzman, Doing it in Parallel (DIP) with the COIN-OR High Performance Parallel Search Framework (CHiPPS), Monash University, Melbourne, Australia, March 2009 (PDF).
- T.K. Ralphs and M. Guzelsoy, Duality in Mixed Integer Linear Programming, University of Canterbury, Christchurch, New Zealand, February 2009 (PDF).
- T.K. Ralphs, Introduction to COIN-OR: Open Source Software for Optimization, University of Canterbury, Christchurch, New Zealand, February 2009 (PDF).
- T.K. Ralphs and M. Guzelsoy, On the Value Function of a General Mixed Integer Linear Program, Victoria University of Wellington, New Zealand, January 2009.
- T.K. Ralphs and S. Denegre, Bilevel Integer Linear Programming, Victoria University of Wellington, New Zealand, January 2009.
- T.K. Ralphs and S. Denegre, Bilevel Integer Linear Programming, University of Auckland, New Zealand, January 2009.
- T.K. Ralphs and S. Denegre, Bilevel Integer Linear Programming, Università degli Studi dell’Aquila, Italy, September 2008 (PDF).
- T.K. Ralphs, Y. Xu, L. Ladanyi, and M.Saltzman, Doing it in Parallel (DIP) with the COIN-OR High Performance Parallel Search Framework (CHiPPS), Graduate Research Seminar, Pennsylvania State University, April, 2008.
- T.K. Ralphs and M. Guzelsoy, The Value Function of a Mixed Integer Program with a Single Constraint, COPTA Seminar, University of Wisconsin-Madison, February, 2008.
- T.K. Ralphs, M. Guzelsoy, J.T. Linderoth, M.J. Saltzman, and M. Wiecek, Biobjective Integer Programming, SAS Institute , June 2006. (PS PDF).
- T.K. Ralphs, M. Guzelsoy, M. Saltzman, and M. Wiecek, Bioobjective Integer Programming, Rutgers University, Department of Industrial and Systems Engineering, Piscataway, NJ, October 2005 (PS PDF).
- T.K. Ralphs and M. Guzelsoy, Duality, Sensitivity Analysis, and Warm Starting, SAS Institute , August 2005. (PS PDF).
- T.K. Ralphs, Making Molehills out of Mountains: A Guided Tour of Large-scale Discrete Optimization, Mathematics Department Colloquium, April 2005. (PS PDF).
- T.K. Ralphs, Capacitated Vehicle Routing and Some Related Problems, Computer Science and Engineering Seminar Series, March 2005. (PS PDF).
- T.K. Ralphs, Integer Programming: A Research Overview , Lehigh IGERT Seminar, September 2004. (PS PDF).
- T.K. Ralphs, Integer Programming: A Research Overview , Lehigh IGERT Seminar, September 2003. (PS PDF).
- T.K. Ralphs, Solving Hard Combinatorial Problems: A Research Overview , Lehigh IGERT Seminar, October 2002. (PS PDF).
- T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A New Framework for Scalable Parallel Tree Search, Lehigh ISE Optimization Seminar, September 2002. (PS PDF).
- T.K. Ralphs, Solving Hard Combinatorial Problems: A Research Overview, Process Modeling and Control Seminar, Department of Chemical Engineering, Lehigh University, March 2002(PS PDF).
- T.K. Ralphs, Decomposition-based Algorithms for Large-scale Discrete Optimization, National University of Singapore, March 2002 (PS PDF).
- T.K. Ralphs, Capacitated Vehicle Routing and Some Related Problems, Rutgers University, Department of Industrial and Systems Engineering, Piscataway, NJ, November 2001 (PS PDF).
- T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A Library Hierarchy for Implementing Scalable Parallel Search Algorithms, Rutgers Center for Operations Research (RUTCOR), Rutgers University, Piscataway, NJ, Sepember 2001. (PS PDF).
- T.K. Ralphs, Branch, Cut, and Price Algorithms for Large-scale Discrete Optimization, National University of Singapore, August 2001 (PS PDF).
- T.K. Ralphs and J.C. Hartman, Capacitated Network Routing, National University of Singapore, August 2001 (PS PDF).
- T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A Library Hierarchy for Implementing Scalable Parallel Search Algorithms, IBM T.J. Watson Research Center, Yorktown Heights, NY, August 2001 (PS PDF).
- T.K. Ralphs, Decomposition-based Algorithms for Discrete Optimization
, IBM T.J. Watson Research Center, Yorktown Heights, NY, August 2001. (slides available by request). - T.K. Ralphs and J.C. Hartman, Capacitated Network Routing , IBM T.J. Watson Research Center, Yorktown Heights, NY, July 2001 (PS PDF).
- T.K. Ralphs, W. Pulleyblank, and L.E. Trotter Jr., A New Generic Separation Algorithm for Combinatorial Optimization, IBM T.J. Watson Research Center, Yorktown Heights, NY, November 1999 (PS PDF).
- T.K. Ralphs, Polyhedral Aspects of the Mixed Postman Problem, Cornell Computational Optimization Project Colloquium, Ithaca, NY, February 1994.
- T.K. Ralphs and L. Ladányi, Computational Experience with a New Heuristic for the Crew Scheduling Problem, Cornell Computational Optimization Project Colloquium, Ithaca, NY, October 1993.
Conference Sessions Chaired
- Open Source and COIN-OR Optimization, International Federation of
Operations Research Societies Triennial Meeting, Barcelona, Spain, July 2014. - Global Optimization and Mixed-Integer Nonlinear Programming, INFORMS Annual Conference, Minneapolis, MN, October 2013
- Multilevel Optimization, INFORMS Annual Conference, Minneapolis, MN, October 2013
- Stochastic Optimization, INFORMS Annual Conference, Minneapolis, MN, October 2013
- Tools and Techniques for Modeling with Python, INFORMS Annual Conference, Phoenix, AZ, October 2012
- Panel Discussion: COIN-OR Technology Forum, INFORMS Annual Conference, Charlotte, NC, November 2011.
- Panel Discussion: COIN-OR Technology Forum, INFORMS Annual Conference, Austin, TX, November 2010.
- Open Source MIP Solvers, The Institute for Operations Research and Management Science Conference, Seattle, WA, November 2007.
- Modeling Languages in the Classroom, The Institute for Operations Research and Management Science Conference, Seattle, WA, November 2007.
- Optimization Software in the Classroom, The Institute for Operations Research and Management Science Conference, Seattle, WA, November 2007.
- Open Source Modeling Tools, The Institute for Operations Research and Management Science Conference, San Francisco, CA, November 2005.
- Integer Programming Software, Institute for Operations Research and Management Science Annual Conference, Denver, CO, October 2004.
- COIN-OR: Software Tools for Optimization, CORS/INFORMS Joint International Meeting, Banff, Alberta, Canada, May 2004.
- Computational Mixed-Integer Programming, CORS/INFORMS Joint International Meeting, Banff, Alberta, Canada, May 2004.
- Open Source Optimization Tools, CORS/INFORMS Joint International Meeting, Banff, Alberta, Canada, May 2004.
- COIN-OR: Software Tools for Implementing Custom Solvers , the Institute for Operations Research and Management Science Annual Conference, Atlanta, GA, October 2003.
- Decomposition and Dynamic Cut Generation, the International Symposium on Mathematical Programming, Copenhangen, Denmark, August 2003.
- COIN-OR: Software Tools for Implementing Custom Solvers , the International Symposium on Mathematical Programming, Copenhangen, Denmark, August 2003.
- Standards and Interfaces in Mathematical Programming, The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002.
- Software Tools for Parallel Processing, The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002.
- Workshop: Software Tools for Implementing Branch, Cut, and Price Algorithms, The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002.
- Branch and Cut Methods , The Institute for Operations Research and Management Science Annual Conference, Miami, FL, November 2001.
- Parallel Discrete Optimization with Applications , International Symposium on Mathematical Programming, Georgia Institute of Technology, August 2000.
Conference Organization
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August 2019
- Program Chair and Organizer, COIN fORgery: Developing Open Source Tools for Operations Research, Institute for Mathematics and Its Applications, Workshop and year-long series of coding sprints.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August 2018
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August 2017
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August 2016
- Stream co-Organizer, Mathematical Optimization, International Congress on Mathematical Software, Berlin, Germany, July 2016
- Sponsored Sessions Chair, INFORMS Annual Meeting, Philadelphia, PA, November 2015.
- Cluster co-Chair, Implementations and Software, International Symposium on Mathematical Programming, Pittsburgh, PA, July 2015
- Program Committee Member, AAAI-15 Workshop on Planning, Search, and Optimization, Austin, TX, January 2015.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, July 2015
- Cluster co-Chair, Implementations and Software, International Symposium on Mathematical Programming, Pittsburgh, PA, July 2015
- Program Committee Member, AAAI-15 Workshop on Planning, Search, and Optimization, Austin, TX, January 2015.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August 2014
- Stream Organizer, Open Source Optimization, International Federation of Operations Research Societies Triennial Meeting, Barcelona, Spain, July 2014.
- Program Committee Member, Constraint Programming, Artificial Intelligence, and Operations Research (CPAIOR), Cork, Ireland, May 2014.
- Cluster Chair, INFORMS Computing Society Cluster, INFORMS Annual Conference 2013, Minneapolis, MN, October 2013.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August, 2013
- Stream Organizer, Integer Programming Stream, INFORMS Computing Society Conference 2013, Santa Fe, New Mexico, January 2013.
- Cluster Chair, INFORMS Computing Society Cluster, INFORMS Annual Conference 2012, Phoenix, AZ, October 2012.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August, 2012.
- Program Committee Member, International Conference on the Integration of Constraint Programming, Artificial Intelligence, and Operations Research (CPAIOR) 2012, Nantes, France, June 2012.
- Program Committee Member, ICORES 2012, Vilamoura, Algarve, Portugal, February 2012.
- Program Committee Member, INFORMS Optimization Society Conference 2012, Miami, FL, February 2012.
- Cluster Chair, Large-scale Computation, The Institute for Operations Research and Management Science Annual Conference, Charlotte, NC, November 2011.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August, 2011.
- Program Chair, MIP 2011, Waterloo, June 2011.
- Program Committee Member, International Conference on the Integration of Constraint Programming, Artificial Intelligence, and Operations Research (CPAIOR) 2011, Berlin, May 2011.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August, 2010.
- Cluster Chair, Computational Optimization and Software, The Institute for Operations Research and Management Science Annual Conference, San Diego, CA, October 2009.
- Program Committee Member, Modeling and Optimization: Theory and Applications (MOPTA), Bethlehem, PA, August, 2009.
- Program Committee Member, INFORMS Computing Society Conference, Charleston, SC, January, 2009
- Stream Chair, Integer Programming, The INFORMS Computing Society Conference, Charleston, SC, January, 2009.
- Cluster Chair, Computational Optimization and Software, The Institute for Operations Research and Management Science Annual Conference, Washington, D.C., October 2008.
- Cluster co-chair, Optimization Services and Open Source Software, The Institute for Operations Research and Management Science Conference, San Francisco, CA, November 2005.
- Program Committee Member, International Workshop of the EURO Working Group on Parallel Processing in Operations Research, Mont Tremblant, CA, January 2005.
Conference Workshops Chaired
- Open Source Tools for Constraint Programming and Mathematical Programming, CPAIOR 2010, Bologna, Italy, June 2010.
Student Supervision
- Ph.D Dissertation Advisor and Committee Chair
- Suresh Bolusani, ISE, TBD.
- Jiadong Wang, ISE, Advances in Integrated Decomposition Methods for Integer Programming.
- Sahar Tahernajad, ISE, Two-stage Mixed Integer Stochastic Bilevel Linear Optimization, December 2019.
- Aykut Bulut, ISE, Computational Methods for Discrete Conic Optimization Problems, December 2017.
- Anahita Hassanzadeh, ISE, Two-stage Stochastic Mixed Integer Optimization, September 2015.
- Scott Denegre, ISE, Interdiction and Discrete Lievel Linear Programming, May 2011.
- Matthew Galati, ISE, Decomposition in Integer Linear Programming, December 2009 (Dissertation).
- Menal Guzelsoy, ISE, Dual Methods in Mixed Integer Linear Programming, December 2009 (Dissertation).
- Zeliha Akca, ISE, Integrated Location, Routing, and Scheduling Problems: Models and Algorithms, December 2009 (Dissertation).
- Ashutosh Mahajan, ISE, On Selecting Disjunctions in Mixed Integer Linear Programming, May 2009(Dissertation).
- Yan Xu, ISE, Scalable Algorithms for Parallel Tree Search, December 2007 (Dissertation).
- Ph.D Dissertation Committee Chair
- Jerry Shen, ISE, Solving Multi-stage Stochastic Linear Programs on the Computational Grid.
- Jim Ostrowski, ISE, Symmetry in Mixed Integer Programming, May 2009.
- Wasu Glankwamdee, ISE, Branch and Bound on Computational Grids, August 2008.
- Kumar Abhishek, ISE, Topics in Mixed Integer Nonlinear Programming, May 2008.
- Ph.D Dissertation Committee Member
- Sertalp Cay, ISE, TBD.
- Sambhawa Priya, CSE, TBD.
- Seyedalireza Yektamaram, ISE, Optimization Algorithms for Machine Learning Designed
for Parallel and Distributed Environments. - Zhengxiang Pan, CSE, Towards a Global Scale Semantic Web.
- Xiaocun Que, ISE, Randomized Algorithms for Nonconvex Nonsmooth Optimization, May 2015.
- Julio Goez, ISE, Mixed Integer Second Order Cone Optimization, Disjunctive Conic Cuts: Theory and Experiments, August 2013.
- Tolga Seyhan, ISE, Network Design Under Competition, May 2012.
- Cagri Latifoglu, ISE, Models for Production Planning and Power Procurement Portfolios, May 2012.
- Udom Janjarassuk, ISE, Using the Computational Grid for the Effective Solution of Stochastic Programs, May 2009.
- Qing Ye, CSE, Dynamic Multicast and Time Synchronization in Wide-area Sensor Networks, December 2007.
- Brian Heinold, Mathematics, Sum List Coloring and Choosability, May 2006.
- Joao Goncalves, ISE, Extensions of von Neumann’s Algorithm for Linear Programming, May 2005.
- Lilong Huang, Chemical Engineering, Constrained Closed-loop Optimal Control, May 2005.
- Jinlong Ban, ISE, Lehigh University, The Generalized Parallel Replacement Problem, December 2003.
- M.S. Advisor
- Shelley Heist, ISE, Lehigh University, Constraint Programming and Sourcing Problems, May 2003.
- Andrew Hofmann, ISE, Lehigh University, The Mixed Postman Problem, May 2003.
Student Awards
- Sahar Tahernejad, Best Poster Award (Honorable mention), Mixed Integer Programming Workshop, Clemson University, June 2018.
- Sahar Tahernejad, Van Hoesen Family Best Publication Award, Industrial and Systems Engineering, Lehigh University, April 2017.
- INFORMS Transportation and Logistics Society Dissertation Prize
- Zeliha Akca, 2010 (runner-up)
- ISE graduate student of the year
- Matthew Galati, 2003
- Menal Guzelsoy, 2004
- Suresh Bolusani, 2017
- Lehigh Engineering Ingenuity Award for Graduate Research and Scholarship
- Matthew Galati, 2004
- Menal Guzelsoy, 2005
- Computational Interface for Operations Research Open Source Coding Contest
- Yan Xu, First Place, 2003
- First Open Contest of Parallel Coding
- Yan Xu and Ted Ralphs, First Place, 2007
Courses Developed and Taught
- ENG 5 Introduction to Engineering Practice.
- IE 170/171/172 Algorithms in Systems Engineering.
- IE 316 Advanced Operations Research Techniques
- IE 372 Systems Engineering Design
- IE 406 Introduction to Mathematical Programming
- IE 411 Graphs and Network Flows
- IE 417 Nonlinear Programming
- IE 418 Integer Programming
- IE 441, Financial Engineering Project
- IE 447 Stochastic Programming and Financial Optimization
- IE 495 Computation in Operations Research
- IE 496 Computational Methods in Optimization
Service
- University
- Computational Optimization Research at Lehigh (COR@L) Laboratory, co-founder and director, September 2004 – present.
- Lehigh Research Computing Steering Committee.
- Co-founder and co-chairman, January 2004 – May 2016.
- Member, May 2016 – present.
- Manager of Research Computing Search Committee, co-chair, January 2014 – June 2014.
- Smart Grid Cluster Hiring Search Committee, September 2011 – May 2013.
- Cluster Hiring Proposal Development Committee: Big Analytics, Co-chair, Fall 2012 (Finalist).
- Cluster Hiring Proposal Development Committee: Computation Science and Engineering, Co-chair, Fall 2011.
- Working Group on Cluster Development (Strategic Planning Front-runner Initiative), March 2010 – May 2010.
- Coordinator of university-wide IBM SUR grant application, September 2007–September 2008.
- Mathematics Search Committee, member, September 2005 – May 2006.
- Major Research Instrumentation Proposal review committee, September 2004 – May 2005.
- College
- CEE Department Chair Search Committee, August 2019 – May 2020.
- CSE Faculty Search Committee, member, September 2013 – May 2014.
- CSE Faculty Search Committee, member, September 2009 – May 2010.
- CSE Faculty Search Committee, member, September 2007 – May 2008.
- RCEAS Tenure Committee, August 2009 – May 2011.
- RCEAS committee on Computational Science and Engineering, August 2009 – June 2010.
- ISE Department Chair Search Committee, member, April 2007 – December 2007.
- RCEAS Dean’s Research Advisory Council, member, January 2007 – May 2008.
- RCEAS Engineering Ingenuity Awards Committee, member, April 2005.
- RCEAS Computational Sciences Committee, member, September 2001 – May 2003.
- RCEAS Mathematics Curriculum Review Committee, member, September 2001 – May 2003.
- RCEAS Freshman Advisor, September 2002 – May 2003.
- Molecular Modeling Search Committee, member, September 2002 – May 2003.
- Chemical Engineering Search Committee, member, September 2001 – May 2002.
- Department
- ISE Faculty Search Committee, Chair, August 2019 – May 2020.
- ISE Professor of Practice Search Committee, Chair, September 2015–May 2016.
- Data Science Strategy Committee, Chair, January 2015–December 2015.
- Undergraduate Curriculum Committee, member, September 2014 – present.
- IT Curriculum Development Subcommittee, Chair, January 2015 – present
- Undergraduate Advisor, September 2011 – present.
- Doctoral Program Curriculum committee, member, December 2010 – present.
- Doctoral Program Admissions Committee, September 2010 – present.
- Doctoral Seminar Series (was the COR@L/INFORMS Seminar Series), founding faculty organizer, September 2002 – present.
- Lehigh Student Chapter of the Institute for Operations Research and Management Science, founding faculty advisor, July 2005 – present.
- Senior Faculty Search Committee, chair, September 2009 – March 2014.
- Co-Director of Graduate Programs, September 2006 – December 2010.
- Junior Faculty Search Committee, member, various times September 2000 – May 2010.
- ISE Council, member, September 2001 – May 2003, September 2005 – 2008.
- ISE Graduate Curriculum Committee, member, September 2001 – May 2008.
- ISE Information and Systems Engineering Curriculum Development Committee, chairman, September 2001 – May 2003.
Professional Activities
- Computational Infrastructure for Operations Research
(COIN-OR) Foundation, co-founder, treasurer, and board member, September
2000–present. - Co-founder
- Strategic Leadership Board, Member
- Technical Leadership Council, Chair
- Former Treasurer
- Institute for Operations Research and Management Science, member, January 1997 – present.
- Member, INFORMS Subdivisions Council, January 2013 – December 2014
- Member, Student Affairs Committee, January 2018 – present
- INFORMS Computing Society, member.
- Harvey J. Greenburg Award Committee, Member, 2019.
- Membership Committee, member, February 2008 – December 2011.
- Board member, January 2010 – December 2011.
- INFORMS Computing Society, Student Paper Prize Committee, Chair, May 2010 – November 2010.
- INFORMS Optimization Society, member.
- Farkas Prize Committee, Member, 2016
- INFORMS Optimization Society, Vice Chair for Computational Optimization and Software, 2007-2009.
- Mathematical Optimization Society, member, January 2000 – present
- Society of Industrial and Applied Mathematics, member, January 2011 – present.
- MIPLIB Steering Committee, member, 2009 -present
- External Reviewer, University of New Brunswick, May 2015 – present.
- Publication Referee
- Annals of Operations Research
- Computers and Operations Research
- Computational Optimization and Applications
- Discrete Optimization
- Discrete Mathematics
- European Journal of Operations Research
- EURO Journal on Transportation and Logistics
- IEEE Control Systems Society
- IEEE Transactions on Computers
- INFORMS Journal of Computing
- International Journal of Operations Research
- International Journal of Computer Mathematics
- International Transactions in Operations Research
- Journal of Global Optimization
- Journal of Experimental Algorithmics
- Management Science
- Mathematical Methods of Operations Research
- Mathematical Programming Series A and B
- Mathematical Programming Computation
- Naval Research Logistics
- Networks
- Operations Research
- Operations Research Letters
- Optimization Letters
- Optimization Methods and Software
- Parallel Computing
- SIAM Journal on Optimization
- The Open Operational Research Journal
- Transportation Science
- Proposal Reviewer
- National Science Foundation
- U.S. Civilian Research and Development Foundation
- Australian Research Council (International Assessor)
- Austrian Science Fund
- National Sciences Engineering and Research Council of Canada
- Former president of the Cornell Operations Research Graduate Association.
- Founding member and first president of the Cornell Graduate and Professional Student Assembly.
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